The present invention relates to a decentered optical system and, more particularly, to a decentered optical system including a rotationally asymmetric surface.
As a conventional observation optical system, Japanese Pat. Appln. Laid-Open (KOKAI) No. 7-333551 proposes a back-coated mirror type decentered optical system using an anamorphic surface and a toric surface as curved surfaces having one plane of symmetry.
However, aberrations due to three-dimensional decentration cannot be corrected in such an optical system that uses curved surfaces having one plane of symmetry as reflecting or other surfaces.